Central sleep apneas, also known as clear airway apneas, are periods when the airway is freely patent but there is no measurable ventilatory effort. These apneas occur due to a lack of neural drive from the brain to the breathing muscles, resulting in pauses in chest or abdominal movement during sleep. Despite the complete absence of airflow, there are brief arousals that typically end with an attempt to breathe. Clear airway apneas are often classified as central apneas, although some experts suggest that they may be better characterized as 'non-obstructive' apneas since they are not caused by upper airway obstruction.
What is Sleep Apnea?
Sleep apnea is a sleep disorder characterized by repetitive pauses in breathing during sleep. This can occur due to several reasons, including central sleep apneas, obstructive sleep apneas (where the airway is partially or completely blocked), or a combination of both. Sleep apneas cause a decrease in oxygen levels and can lead to a range of health problems, including obstructive sleep apnea, central sleep apnea, high-altitude pulmonary edema (HAPE), and death.
Types of Sleep Apneas
There are three main types of sleep apneas: central, obstructive, and mixed. Central sleep apneas are often associated with underlying medical conditions but can also occur in healthy individuals. Obstructive sleep apneas are caused by obstructing the upper airway during inspiration, leading to loud snoring and gasping spells. Mixed apneas are a combination of central and obstructive apneas.
Measurement of Sleep Apneas
Sleep studies, such as polysomnography (PSG), are used to diagnose sleep apnea by objectively measuring the number of sleep apneas and hypopneas per hour of sleep. The apnea-hypopnea index (AHI) is a quantitative measure of sleep-disordered breathing severity based on the average number of apneic and hypopneic events per hour. An AHI of 5-15 is considered mild sleep apnea, 15-30 is moderate, and over 30 is severe.
Clear Airway Apneas versus Obstructive Apneas
While both central and obstructive apneas disrupt normal breathing, they differ in several key aspects:
- Respiratory Effort: Central apneas lack breathing efforts, whereas obstructive apneas involve a struggle against an obstructed airway.
- Airflow Reduction: Central apneas involve complete or near-complete cessation of airflow, while obstructive apneas involve partial obstruction.
- Oxygen Desaturation: Both types of apneas typically have larger drops in oxygen saturation compared to hypopneas.
- Sleep Stage Pattern: Central apneas are most common during REM sleep, while obstructive events occur across all sleep stages.
- Anatomical Causes: Central apneas stem from neurological abnormalities, while obstructive apneas are caused by physical obstructions of the upper airway.
Treatment of Sleep Apneas
Treatment for sleep apneas typically involves a combination of lifestyle changes, medical devices, and, in some cases, surgical procedures. Positive airway pressure (PAP) devices, such as continuously可调的持续正压通气 CPAP 和双水平正压通气 BiPAP, are the primary treatment for obstructive sleep apnea. Custom-made oral appliances, like mandibular advancement devices, may be helpful for mild to moderate obstructive apnea. For central sleep apneas, managing underlying comorbidities and optimizing PAP therapy are essential.
Health Implications of Untreated Sleep Apnea
Ignoring sleep apnea can lead to significant health issues, including obstructive sleep apnea, high-altitude pulmonary edema, stroke, and arrhythmias. Additionally, symptoms such as snoring, fatigue, and cognitive difficulties can affect quality of life and increase risk of accidents. Therefore, accurate diagnosis and treatment are crucial for mitigating long-term health后果, including cardiovascular disease, metabolic disorders, and memory loss.
##Central sleep apneas are a subset of sleep apneas that lack neural drive, resulting in complete pauses in breathing during sleep. While non-obstructive in nature, these apneas can still have significant clinical implications. Recognizing clear airway apneas and addressing their underlying causes is vital for mitigating associated health risks and improving overall sleep quality and daytime function.
